Third region? Sorry, they didn't put in hoenn/sinnoh in HG/SS..
You cannot go to the Sinnoh region in "Pokémon HeartGold" and "Pokémon SoulSilver."
No, you cannot get to the Hoenn region in Pokémon SoulSilver.
Johto
Not in Heartgold/Soulsilver.
The third gym leader is Whitney.
there is not a new region its in johto
in the sinnoh region in Soulsilver.
No
You can't.
No.
Johto.
You cannot get to the Hoenn region in Pokémon SoulSilver, the only regions that are available in SoulSilver are Johto and Kanto regions.